^^this^^

Edit: I was speaking to the use of bondo or autobody filler to plug  the rat holes for AESS or sealing purposes vs using weld metal to fill the rat hole(aka Weld Access Hole).

My hesitation in just coming out and saying this Scott, is that it was not called a "weld access hole", only, an 'access hole'. 

But that is the direction I was heading by asking the questions that I did.  More information is needed about what is actually going on.

To the OP, also, if this is weld access holes per D1.1 and/or D1.8, there are better ways to consider for 'sealing' than filling them which would make you weld in the k-area which is exactly why the weld access holes exist in the first place, TO KEEP YOU OUT OF THE K-AREA. 

You can wrap these 'corners' without actually 'filling' the weld access hole. 

On the other hand, if we are only talking about standard D1.1 corner clips for the radius of the W-shape member (which IS NOT the k-area by the way and there will soon be an article in IT about this) then while you CAN weld that area, it is not wise to do so.  Better to make a larger corner clip and wrap around without getting into the radius or even the k-area. 

Just a couple of thoughts while awaiting more info.

Have a Great Day,  Brent.

Following Lawrence on this....AGA has recommendations about seal welding

From the AGA website:
Seal welding
Complete seal-welding can be used so the cleaning solutions cannot penetrate the overlap surfaces. When a weld joint is completely sealed, there must be no weld imperfection or pinholes. The penetration of moisture into the sealed cavity could cause significant safety hazards during the hot-dip galvanizing process as the sealed air will greatly expand when the part reaches the galvanizing temperature. This gas expansion can cause the molten zinc to splash out of the bath and endanger galvanizing workers. If the area of a seal-weld overlap is large, there should be vent holes through one or both sides into the lapped area. This is to prevent any moisture that gets in through a pinhole in the weld from building up excessive pressure while in the galvanizing bath. This venting becomes more important the greater the area. Consult your galvanizer or the AGA publication Recommended Details for Galvanized Structures for vent size and quantity. Vent holes can be sealed after galvanizing.

Gentlemen,

I have a copy of this in my records somewhere.  I will pull out my thumb drives and see what I can find and if I can document where I found it.

Note though, one aspect of it is that the size of most 'seal welds' is so small/thin compared to base material and other welds that expansion and contraction rates have been shown to be so different between those that the potential for cracking is extreme.  And that multiplies even more if the tiny seal weld is then ground to make it really smooth. 

I will look for it but am pretty busy the next few days.  You might have to remind me.

Have a Great Day,  Brent